The present invention relates to photonics chips and, more specifically, to structures for an electro-optic modulator and methods of fabricating such structures.
Photonics chips integrate optical components and electronic components into a single chip. Photonics chips are capable of being used in many applications and many systems including, but not limited to, data communication systems and data computation systems. The electronic components may include, for example, field-effect transistors, and the optical components may include waveguides. Layout area, cost, and operational overhead may be reduced by including both types of components on a single photonics chip.
On-chip communication and sensing may rely on transferring electromagnetic radiation through silicon waveguides in the mid-infrared wavelength range of 3 microns (μm) to 8 μm. Silicon waveguides may be fabricated from the single-crystal silicon contained in the device layer of a semiconductor-on-insulator (SOI) wafers. The buried insulator layer of the SOI wafer, which is typically composed of silicon dioxide, provides cladding for the silicon waveguides. Silicon waveguides may experience signal loss because the silicon dioxide of the buried insulator layer strongly absorbs electromagnetic radiation starting at a wavelength of 3.5 μm in the mid-infrared wavelength range.
Improved structures for an electro-optic coupler, as well as methods of fabricating such structures, are needed.